Peterson was carried from the field last week in his side's defeat to the Baltimore Ravens but tests revealed that his ailment was not as serious as first predicted and is now questionable to face the Philadelphia Eagles.
"It was impressive when you consider the early diagnosis," Frazier told the Minneapolis Star Tribune. "He's unique. Very unique. He's so different than everybody else when it comes to recovering from injuries.
"We've been in situations in the past where you thought he wouldn't make it and he made it. So it was always in the back of my mind the chance he would make it. He's amazing."
The Vikings are 3-9-1 in their season going into week 15.